1. Field of the Invention
The disclosed embodiments of the present invention relate to cell balancing, and more particularly, to an active balancing circuit for balancing battery units by providing the battery units with energy of battery unit(s) having higher voltage(s) in the battery units.
2. Description of the Prior Art
In order to supply a higher output voltage, a plurality of batteries may be coupled in series as a power supply to provide the required output voltage. However, when the power supply having the series-connected batteries is charged, voltage unbalance between the batteries will lower the total energy or damage the power supply. For example, when a part of the batteries in the power supply are fully charged and the rest of the batteries need a period of time to complete charging, continuing charging the power supply may lead to overcharging of the part of the batteries, thereby shortening the life of the part of the batteries.
A conventional power supply uses a passive battery balancing mechanism to prevent overcharging. The passive battery balancing mechanism, however, consumes excess energy (i.e. overcharge energy), resulting in energy waste and excess heat. Thus, an active balancing circuit is needed to solve the above problems.